Cohen resigned as chairman and chief executive officer of Warner Music Group's recorded music operation to start 300 with Todd Moscowitz, ex-Warner Bros president, Kevin Liles, ex-EVP Warner Music, and Roger Gold, former SVP of the office of the chairman and CEO at Warner Music. Cohen, Liles, and Moscowitz had also worked together at Def Jam, which Cohen had run in the 1980s and 1990s.[2]

It was announced that singer Eric Bellinger had been signed to 300 Entertainment.[3] In April 2014, Atlantic Records A&RDJ Drama stated that Atlanta rapper Young Thug had been signed to 300 Entertainment,[4][5] In June 2014, it was revealed that Atlanta hip hop group Migos were also signed to the label.[6] In early 2014, Lyor Cohen quietly signed Conrad Sewell after Sewell had been passed on by most of the major labels. The day after signing with 300, the Australian singer received offers from virtually every label that had passed on him, for, in some cases, "well over $1 million."[7]

In September 2016, Lyor Cohen announced his exit from 300.[11] Following this announcement, Kevin Liles assumed the role of CEO.[12] Liles would make appearances to follow in The Wall Street Journal and on MSNBC to discuss his role and the label.[13]

In September 2017, Hopsin did an interview with HardKnocktv stating that he had signed with 300. His single "The Purge" was released through 300 Entertainment and Undercover Prodigy.[20]
On November 24, 2017, Hopsin Released his album No Shame and debuted at 42 on the Billboard 200. Both Kevin Liles and Hopsin has referred to the deal as a partnership for 300 and Undercover Prodigy.